A standard such inductive sensor has an outer fixed field winding energized by alternating current and a coaxial inner detecting winding that is displaceable axially in the field winding and that has no ferromagnetic core. A link arrangement axially displaces the inner winding with the object whose position is being detected. The voltage induced in the detecting winding is used to establish the position of the thing whose position or motion is being detected, the absolute value of the voltage indicating position and the slope of the voltage/time curve indicating displacement speed.
As a result of the inevitable internal and external disturbances of the magnetic field as well as of the nonhomogeneous form of the magnetic field, the sensitivity of these devices does not satisfy strict requirements. For instance changes in temperature can change the conductivity of the wire of the coils, affecting their inductance, or variations in the voltage or frequency of the feed current may be reflected in the readings. Only the most complex and hence failure-prone circuits can repress the effects of outside disturbances enough to make such a sensor highly accurate.